1. Field of the Invention
The invention is based on a fuel injection valve for internal combustion engines, preferably self-igniting internal combustion engines.
2. Description of the Prior Art
One fuel injection valve or the type with which this invention is concerned is known from International Patent Disclosure WO 96/19661. In this known valve, a blind bore in which a valve member is guided is embodied in a valve body. The valve member is surrounded on its portion toward the combustion chamber by a pressure chamber which can be filled with fuel at high pressure. A conical valve seat is embodied on the bottom face of the blind bore, toward the combustion chamber. Moreover, at least one injection port, which connects the bore to the combustion chamber, is embodied on the bottom face.
In the closing position, the valve member with its valve member tip comes into contact with the valve seat and thus closes the injection ports off from the pressure chamber. Two conical faces are disposed on the valve member tip, and at their transition an encompassing annular groove is formed, which defines the effective seat diameter of the valve member and has the effect that the opening pressure of the fuel in the pressure chamber during operation does not change. The result is a constant, replicable injection quantity and thus optimal combustion, as long as the valve member moves in a precisely centered way in the bore.
If the valve member is not precisely axially aligned, the inflow of fuel from the pressure chamber at the conical faces of the valve member tip and past the sealing edge to the injection ports is no longer symmetrical. The injection ports, relative to which the valve member is also off its axis, are covered at the onset of the opening stroke motion by the valve member, so that no fuel or only very little fuel can flow to them. Only in the course of the complete opening stroke motion of the valve member are the initially covered injection ports uncovered, and only then can the fuel also flow through these injection ports. The consequence is a reduction in the total injected fuel quantity and thus a power loss to the engine.
The uneven injection into the combustion chamber also causes an air-fuel mixture that is supersaturated with fuel to form in some regions of the combustion chamber volume, while in other regions there is too little fuel in proportion to the existing air. In the supersaturated regions, incomplete combustion accordingly takes place, with the well-known adverse effects on the concentration of pollutants in the exhaust gas.